The formation of a metallosupramolecular porous helicate through salicylaldehydethiosemicarbazone: Synthesis, Characterization, Cytotoxic activity, DNA binding and DFT calculations

Article abstract of DOI:10.1002/aoc.5023

The reaction of salicylaldehyde-S-methylisothiosemicarbazone in the presence of ethylenediamine base and iron (III)chloride generated unforeseen homotopic dinuclear triple-stranded iron (III)helicate. The synthesized helicate was characterized by elemental analysis, IR, UV–Vis spectroscopy, magnetic moment measurement, and evaluated cytotoxic activities against K562, HL-60 and THP-1 leukemia cells. In addition, solid-state structure has been determined by single-crystal X-ray diffraction technique. In the complex, three dinucleating O, N, N, O donor ligands provide three diazine (═N─N═) bridges between the metal ions and facial O₃N₃ coordination spheres around them. The ligands are folded about the N─N single bond and coordinated to the two metal ions in a helical fashion to form the triple helical structure. In the crystal lattice, chains of centrosymmetric R² ₂(12) rings, which are connected to one another via π─π stacking interactions, are generated by C─H···O intermolecular interactions. The results are also confirmed by the density functional theory (DFT) calculations. The results obtained from the cytotoxicity test showed to be effective in low concentrations on the leukemia cells. An intercalative binding mode of helicate-DNA complex was confirmed with the high intrinsic binding constant (K_b?=?8×10⁶ M^?1) and competitive displacement assay of Ethidium bromide with high Ksv value.

Full text of DOI:10.1002/aoc.5023

Received: 27 February 2019
DOI: 10.1002/aoc.5023
Revised: 30 April 2019
Accepted: 9 May 2019
F U L L P A P E R
The formation of a metallosupramolecular porous helicate
through salicylaldehydethiosemicarbazone: Synthesis,
Characterization, Cytotoxic activity, DNA binding and DFT
calculations
Elif Avcu Altiparmak1
Serap Erdem Kuruca5
| Guneş Ozen Eroglu2
| Elif Ozcelik3
| Nergis Arsu3 | Bahri Ülküseven1
| Namık Özdemir4
| Tulay Bal‐Demirci1
|
1 Department of Chemistry, Engineering
Faculty, Istanbul University‐Cerrahpaşa,
34320 Istanbul, Turkey
2 Department of Molecular Medicine, Aziz
Sancar Institute of Experimental
Medicine, Istanbul University, 34093
Istanbul, Turkey
3 Chemistry Department, Yildiz Technical
University, Davutpasa Campus, 34220
Esenler, Istanbul, Turkey
4 Department of Mathematics and Science
Education, Faculty of Education,
Ondokuz Mayıs University, 55139
Samsun, Turkey
The reaction of salicylaldehyde‐S‐methylisothiosemicarbazone in the presence
of ethylenediamine base and iron (III)chloride generated unforeseen
homotopic dinuclear triple‐stranded iron (III)helicate. The synthesized helicate
was characterized by elemental analysis, IR, UV–Vis spectroscopy, magnetic
moment measurement, and evaluated cytotoxic activities against K562, HL‐60
and THP‐1 leukemia cells. In addition, solid‐state structure has been deter-
mined by single‐crystal X‐ray diffraction technique. In the complex, three
dinucleating O, N, N, O donor ligands provide three diazine (═N─N═) bridges
between the metal ions and facial O3N3 coordination spheres around them.
The ligands are folded about the N─N single bond and coordinated to the
two metal ions in a helical fashion to form the triple helical structure. In the
crystal lattice, chains of centrosymmetric R22ð12Þ rings, which are connected
to one another via π─π stacking interactions, are generated by C─H···O inter-
molecular interactions. The results are also confirmed by the density functional
theory (DFT) calculations. The results obtained from the cytotoxicity test
showed to be effective in low concentrations on the leukemia cells. An
intercalative binding mode of helicate‐DNA complex was confirmed with the
high intrinsic binding constant (Kb = 8×106 M−1) and competitive displace-
ment assay of Ethidium bromide with high Ksv value.
5 Department of Physiology, Faculty of
Medicine, Istanbul University, 34093
Istanbul, Turkey
Correspondence
Tulay Bal‐Demirci, Department of
Chemistry, Engineering Faculty, İstanbul
University‐Cerrahpaşa, 34320 İstanbul,
Turkey.
Email: tulaybal@istanbul.edu.tr
Funding information
Ondokuz Mayıs University, Grant/Award
Number: PYO.FEN.1906.19.001; Scientific
Research Projects Coordination Unit of
İstanbul University, Grant/Award Num-
ber: FYL‐2017‐23739
KEYWORDS
cytotoxicity, DFT, DNA binding, Helicate, supramolecular
1 | INTRODUCTION
Supramolecular chemistry is one of the most actual
subjects of recent times. Supramolecular structures are
Thiosemicarbazones have attracted a great deal of atten-
tion due to reaction capability with metal ions, biological
activities, DNA interactions, ability in analytical and sen-
sor applications, catalytic activities for a long time.[1–8]
self‐assembled through multiple weak intermolecular
interactions, such as hydrogen bonding, π‐π stacking
and strong dipole–dipole association, hydrophobic inter-
actions and host‐guest interactions.[9–12] The ultimate goal
Appl Organometal Chem. 2019;e5023.
wileyonlinelibrary.com/journal/aoc
© 2019 John Wiley & Sons, Ltd.
1 of 14
https://doi.org/10.1002/aoc.5023

2 of 14
AVCU ALTIPARMAK ET AL.
in supramolecular chemistry is to mimic the achievement
of biological systems such as tobacco mosaic virus, poly-
peptides, and DNA, examples of self‐assembly in nature.
Self‐organization processes direct the assembly of one,
two or three‐dimensional architectures by information
stored in the covalent framework. Self‐assembly process
is kinetically rapid and generates the most thermodynam-
ically stable product. In addition, self‐assembled
metallosupramolecules are known to have anticancer
activity, to interact with DNA and proteins and to behave
as selective sensors for biologically important.[13–15]
One of the most well‐known examples of self‐
assembling supramolecular systems is helicates. Helicates
are helical structures formed by self‐assembly that ligands
having more than one donor atom its framework are
stranded around two or more metal atoms. Fundamental
functions of supramolecular structures are to molecular
recognition, transformation and translocation. Helicates,
have cavities in their structures known as metal–organic
frameworks,[16] behave as host and are able to encapsu-
late guest molecules as cations, anions, water, fullerenes,
bipyridines.[10,17–21] These properties make them valuable
in the field of medicine. In drug design, new metal com-
plex structures having a high binding affinity with DNA
is of increasing importance.[22] There have been many
studies on anticancer[23] and antimicrobial[24] activity of
helicates recently.
The aim of many studies is to identify new anticancer
agents with greater selectivity to cancer cells. Hotze and
colleagues reported a DNA‐binding iron (II) helicate
of anticancer activity.[25,26] It is commonly believed
that DNA is the main target of many anticancer
agents.[15,22,27] The study of interactions between the anti-
cancer agents and DNA is important to in order to under-
stand the mechanism of their anticancer activities. Types
of interactions between the drug and DNA can be catego-
rized into non‐covalent binding including electrostatic
interaction, groove binding, intercalation, covalent‐
binding and strand breaking, or as a sort of their combi-
nations. Molecules can bind with DNA such as a single
mode or mixed modes of binding.[28–30]
many traditional agents but act by inducing cell cycle
arrest and apoptosis. They show high activity in resistant
cell line A2780cis (cisplatin‐resistant ovarian carci-
noma).[33] In another study, an arginine‐decorated analog
showed slightly higher cytotoxicity than the parent
compound against A2780 ovarian cancer cells (IC50:
∼7 μM).[34] Beside iron helicates, metallosupramolecular
ruthenium complexes have been notified that are been
very active against cancer cell lines: with their potencies
ranging from being similar to that of cisplatin to being
as much as 100 times more potent. Li et al. showed
metallosupramolecular polymers prepared with ruthe-
nium (II) or iron (II) ions high binding ability to several
DNAs by UV–Vis absorption titration experiments. The
electrostatic interactions between the metal cations of
the polymers and phosphate anions of DNA led to the
formation of conjugate structure.[35] Therefore, it is nec-
essary to introduce new compounds as anticancer drug
candidate[36,37] and more simple techniques.
In this paper, we synthesized a homotopic helicate
unexpectedly from the reaction of ethylenediamine,
salicylaldehyde‐S‐methylisothiosemicarbazone and iron
(III)chloride (Scheme 1). This compound is hitherto
the first helicate formation through a decomposed
thiosemicarbazone structure according to our current
knowledge. The obtained structure is characterized by
spectroscopic methods, and its crystal structure has been
determined by x‐ray crystallography. Furthermore, den-
sity functional theory (DFT) calculations have been car-
ried out to support experimental findings. The results
obtained from cytotoxicity test showed that synthesized
iron (III) helicate is to be effective in low concentrations
on different leukemia cells (K562, HL60 and THP‐1). In
addition, we firstly reported binding iron (III) helicate
to ct‐DNA (calf thymus DNA) by intercalation. Exhibi-
tion of the binding mode of helicate to DNA will help
to understand the anticancer efficiency and to develop
novel chemotherapeutic agents.
Hannon and co‐workers have developed an extensive
family of metallosupramolecular helicates which interact
with DNA in a number of ways and show activity against
cancer cell lines.[31] Triplex metallohelices were highly
active against colon cancer cell lines in nanomolar con-
centrations and but with lower activity against others,
and showed no activity against normal cells. This kind
of selectivity is very unusual and indicates a subtle biomi-
metic mechanism. Dramatic effects on the cell cycle and
the promotion of early apoptosis were observed, but no
DNA damage was detected in a range of studies.[32]
Flexicates do not damage DNA in cancerous cells like
SCHEME 1 The formation of the helicate

AVCU ALTIPARMAK ET AL.
3 of 14
2 | EXPERIMENTAL AND
2.2 | Chemicals and apparatus
COMPUTATIONAL METHODS
All chemicals were of reagent grad and used as
commercially purchased without further purification.
The elemental analyses were determined on a Thermo
Finnigan Flash EA 1112 Series Elemantal Analyzer. IR
spectra of the compounds were recorded on Cary 630
FTIR spectrometer with Diamond ATR from Agilent.
The 1H Nuclear Magnetic Resonance spectrum was
recorded in DMSO on Bruker AVANCE‐500 model
spectrometer. Ultraviolet–Visible spectra (UV–Vis) were
obtained with Shimadzu UV‐2600 Spectrophotometer as
5×10−5 M solutions in CHCl3.
2.1 | Synthesis
2.1.1 | Synthesis of
salicylaldehyde‐S‐
methylisothiosemicarbazone (starting
material)
Starting material was prepared by reaction of 2‐
hydroxybenzaldehyde and S‐methylthiosemicarbazide
according to lit.[38] method in methanol. The resulting
yellow product was dried under vacuum. Characteriza-
tion data of the starting material: The Color: Light Yel-
low; Yield: 91%; m.p. (°C): 160–161; Anal. Calc. for
C9H11N3OS (209.27 g/mol): C, 51.65; H, 5.30; N, 20.08;
S, 15.32; Found: C, 51.49; H, 5.12; N, 21.14; S, 15.08%.
IR (cm−1): 3458 υsym (NH2); 3281 υasym (NH2); 1633 δ(N‐
H); 1601 υ(C=N); 1147 υ(C‐O); 2925, 2780 υ(C‐H). UV–
Vis (5.10−5 M, CHCl3): ((λ (ε)) 239.5 (16420), 293
2.3 | X‐ray crystallography
Intensity data of the complex were collected on an STOE
IPDS II diffractometer at room temperature using
graphite‐monochromated Mo Kα radiation by applying
the ω‐scan method. Data collection and cell refinement
were carried out using X‐AREA[39] while data reduction
was applied using X‐RED32.[39] The structure was solved
by a dual‐space algorithm using SHELXT‐2018[40] and
refined with full‐matrix least‐squares calculations on F2
using SHELXL‐2018[41] implemented in WinGX[42]
program suit. All H atoms bonded to C atoms were posi-
tioned geometrically and refined as a riding model with
C─H = 0.93 Å. The displacement parameters of the H
atoms were fixed at Uiso(H) = 1.2Ueq of their parent
atoms. Crystal data, data collection and structure refine-
ment details are collected in Table 1. Molecular graphics
were created by using ORTEP‐3.[42]
1
(21900), 304.5 (21120), 333.5 (21780), 346.5sh (16890). H
NMR (ppm): 11.58, 10.69 (s, i:1:2, 1H, OH), 8.45, 8.31
(s, 1H, i:1:2, CH=N1), 7.44 (d, 1H, J = 7.44, (d)); 7.19
(m, 1H, (b)); 6.88 (s, 2H, (a,c)); 6.92 (s, 2H, NH2); 2.39
(s, 3H, S‐CH3).
2.1.2 | Dinuclear iron (III) complex of tris
(N1, N2‐bis‐(2‐hydroxy‐benzaldehyde)‐
hydrazone); [Helicate]
The complex is prepared by reaction of 2‐hydroxy‐benzal-
dehyde‐S‐methylthiosemicarbazone,
ethylenediamine
and FeCl3.6H2O in methanol. Ethylenediamine ( 0.2
ml, 3 mmol) was added to starting material (0.2 g,
1 mmol) in 10 ml methanol and refluxed. After ten
minutes of reflux, FeCl3.6H2O ( 0.27 g, 1 mmol) was
added to the solution and the mixture was continued
to reflux for 72 hrs and dark‐brown solution formed.
The resulting product was filtered off and crystallized
as acicular in CHCl3. Dark brown crystals were dried
under vacuum. Characterization data of the helicate:
The color: Dark Brown; Yield: 31%; m.p. (°C): >350; μeff
(BM): 6.02; molar conductivity (in 10−3 M DMSO, ohm
2.4 | Cytotoxicity test
The HL‐60 human promyelocytic leukemia cell line, K562
human chronic myeloid leukemia cell line, THP‐1 human
acute monocytic leukemia cell line, were obtained from
the American Type Culture Collection (VA, U.S.A.). Nor-
mal peripheral blood mononuclear cells (PBMC) were
obtained from the whole blood sample taken from healthy
people and cultured. The PBMCs were separated from the
whole blood sample using Histopaque® 1077 (Sigma‐
Aldrich Chemical Co., St. Louis, MO) according to the
lymphocyte separation protocol. All cells were cultured
according to the standard procedure and maintained in a
RPMI‐1640 medium (Sigma, Chemical Co., St. Louis,
MO) supplemented with 10% FBS (Biological Industries)
and 1% penicillin/streptomycin. Cell count was deter-
mined by the trypan blue dye exclusion test. To assess
−1
cm2 mol−1): 1.4; Anal. Calc. For C42H30Fe2N6O6
(826.41 g/mol): C, 60.73; H, 3.62; N, 10.48; Found: C,
60.98; H, 3.65; N, 10.17%. UV–Vis (5.10−5 M, CHCl3)
λ
max(ε): nm (mM−1 cm−1)): 240 (20020), 280.5 (16940),
377 (6900), 444.5 (2360), 514.5 (2360). FT‐IR (cm−1):
1598, 1573 υ(C=N); 1144, 1121 υ(C‐O); 2928, 2657 υ(C‐
H); 1249 υ(N‐N).

4 of 14
AVCU ALTIPARMAK ET AL.
TABLE 1 Crystal data and structure refinement parameters for
Helicate
Each concentration was tested in triplicate using
10 μl/well added to the 90 μl of cells in complete medium.
DMSO was added to the control wells as 0.1%. The plates
were incubated for 72 hrs and the evaluation of cell pro-
liferation was performed by the MTT (3‐(4,5‐dimethyl-
CCDC deposition no.
Colour/shape
1867923
Dark brown/prism
[Fe2(C14H10N2O2)3]
826.42
Chemical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
thiazol‐2‐yl)‐2,5‐
diphenyl‐2H‐tetrazolium
bromide)
colorimetric assay.[43]
10 μl MTT solution (5 mg ml−1 in PBS, Sigma, Chem-
ical Co., St. Louis, MO) was added to each well and incu-
bated for 3.5 hours. Formazan crystals were solubilized in
200 μl DMSO. Optical density was measured using a
microplate reader at 560 nm to reference wavelength
620 nm.
296(2)
0.71073 Mo Kα
Monoclinic
I2/a (No. 15)
Unit cell parameters
a, b, c (Å)
Viability percentage was determined according to
absorbance by using the following equation (1).
15.3927(10), 20.4752(15),
12.5531(8)
α, β, γ (°)
Volume (Å3)
Z
90, 114.018(5), 90
Mean absorbance of sample
3613.8(4)
Viability ð%Þ ¼
× 100 (1)
Mean absorbance of control
4
Dcalc (g/cm3)
1.519
Cell viability data were analyzed using the unpaired t‐
test and presented as mean SD for n = 3 and compari-
son of the data by GraphPad Prism 5.04 software. P < 0.05
was considered significant.
μ (mm−1
)
0.863
F 000
1696
Crystal size (mm3)
0.58 × 0.25 × 0.14
Diffractometer/measurement STOE IPDS II/rotation (ω scan)
method
2.5 | Computational details
Index ranges
−18 ≤ h ≤ 18, −24 ≤ k ≤ 23,
−14 ≤ l ≤ 14
The computational results were obtained using the
Gauss‐View 5.0 molecular visualization program[44] and
Gaussian 09
θ range for data collection (°) 1.757 ≤ θ ≤ 25.048
W
program package.[45] The density
Reflections collected
15107
functional theory (DFT) calculations were carried out at
the B3LYP[46,47] level of theory with 6 − 311G (d,
p)[48,49] basis set for the main group elements and
LANL2DZ[50–52] basis set for the iron core. All the
geometry optimizations were followed by frequency
calculations and no imaginary frequencies were found,
approving the stable nature of the optimized structures.
A scale factor of 0.9679[53] has been used to correct the
calculated harmonic vibrational frequencies.
Independent/observed
reflections
3206/1905
Rint
0.132
Refinement method
Data/restraints/parameters
Goodness‐of‐fit on F 2
Final R indices [I > 2σ(I)]
R indices (all data)
Δρmax, Δρmin (e/Å3)
Full‐matrix least‐squares on F 2
3206/0/253
0.948
R1 = 0.0590, wR2 = 0.1255
R1 = 0.1054, wR2 = 0.1442
0.58, −0.31
2.6 | DNA binding studies
Calf thymus DNA (Activated Type XV ct‐DNA), Tris‐
hydrochloride, Ethidium Bromide (EB) solution (10 μL/
1 ml) were supplied from Sigma (Chemical Co., St. Louis,
MO, USA). The stock solution in Tris–HCl (pH: 7.0)
buffer was used for the preparation of the diluted
solutions and left in a refrigerator at 4 °C. Analytical, A.
C.S. or reagent grade chemicals and twice distilled water
were used.
the cytotoxicity, HL‐60, K562 and THP‐1 cells were grown
in 96‐multiwell flat bottom microtiter plates (SPL Life Sci-
ences) as 10000 cells/100 μL of complete medium per well.
PBMC were also seeded in the same conditions. The stock
solution of the helicate (5 mg ml−1, DMSO) was prepared
and directly used for dilutions. The dilutions were pre-
pared in complete medium. The range of final concentra-
tions for the helicate was 1, 3.5, 5, 7, 10 μg ml−1 in
microplate wells. Vincristine was used as a positive control
by dissolving the commercial form in distilled water.
UV–Visible Varian Carry 50 Spectrophotometer was
used for recording the absorption spectra. Jobin Yvon‐
Horiba Floromax‐P was used for recording of the

AVCU ALTIPARMAK ET AL.
5 of 14
fluorescence emission spectra. The widths of the excita-
tion and emission slits were set at 1.5 nm. WTW,
pH/cond. 340i pH meter was used for the pH
measurements.
2.6.3 | UV–vis spectroscopic
measurements
The UV–Vis spectra of helicate and the mixture of
helicate and ct‐DNA were recorded from 240 to 800 nm.
Titration of the fixed amount of helicate was achieved
with various amounts of ct‐DNA. The 2.5 mL solution
containing helicate was stirred thoroughly after each
DNA addition in varying amounts. The initial concentra-
tion of ct‐DNA was 28 μM. The helicate ‐DNA solution
was left to stand for 2 min. to reach equilibrium, then
UV–Vis measurements were recorded. All UV–Vis spec-
tra were performed using both 10 mmol L−1 Tris–HCl
(pH: 7.0).
2.6.1 | Preparation of ct‐DNA and Helicate
solution
Tris–HCl buffer solution was prepared from
tris‐(hydroxymethyl)‐amino‐methanehydrochloride with
doubly distilled water and pH was adjusted to 7.0. Calf
thymus DNA (ct‐DNA) was used without further purifi-
cation dissolved in 10 mmol L−1 Tris–HCl (pH:7.0) buffer
solution. The concentration of the ct‐DNA solution was
found to be 2.06×10−2 mol L−1. The UV–Vis absorbance
at 260 nm and the molar absorption coefficient of
ɛ260 = 6600 L mol−1 cm−1 were used in order to
determine the concentration of ct‐DNA. The purity of
the ct‐DNA was checked by recording the ratio of the
absorbance at 260 nm to that at 280 nm. The obtained a
ratio of A260/A280 = 1.80, indicates that DNA was suffi-
ciently free from protein.[54–56]
2.6.4 | Fluorescence spectroscopic
measurements
Fluorescence emission spectra of the individual helicate
and the mixture of helicate and ct‐DNA solutions were
recorded from 300 nm to 590 nm (λexc = 320 nm). Titra-
tion of the helicate with the increasing amount of ct‐DNA
was achieved. The initial concentrations of helicate and
ct‐DNA were 62 μM and 28 μM, respectively. The
2.5 ml solution containing helicate was stirred thoroughly
after each DNA addition in varying amounts. The
helicate‐DNA solution was left to stand for 2 min. to
reach equilibrium, then fluorescence measurements were
The stock solution of helicate (62 μΜ = 51.3 μg/ml)
was made up by dissolving its crystals both in
10 mmol L−1 Tris–HCl buffer.
2.6.2 | Absorption properties
The prepared aqueous solution of helicate in 10 mM Tris–
HCl (pH:7.0) was used for recording absorption spectra
before and after addition of increasing concentrations of
ct‐DNA solution. A graph was plotted with concentration
against absorbance.
The intrinsic binding constant Kb was determined
according to the following equation (2). It is very impor-
tant to get information about the intrinsic binding
constant to learn about binding type between helicate
and DNA.
½DNAꢀ=ðεa − εf Þ ¼ ½DNAꢀ=ðεb − εf Þ þ 1=Kb ðεb − εf Þ (2)
Where [DNA] is the concentration of DNA in the
nucleotides, the appearance of absorption coefficients εa,
εf and εb corresponds to Aobsd/ [M], the extinction coeffi-
cient observed at a given DNA concentration, the extinc-
tion coefficient of the free compound and the extinction
coefficient of the compound when fully bound to DNA,
respectively. In the plots of [DNA]/(εa‐εf) versus [DNA],
Kb is given by the ratio of the slope to the intercept.[57,58]
FIGURE 1 The molecular structure of the complex showing the
atom‐numbering scheme. Displacement ellipsoids are drawn at
the 10% probability level and H atoms have been omitted for clarity
[Symmetry code: i − x + 3/2, y, −z + 1]

6 of 14
AVCU ALTIPARMAK ET AL.
recorded. All fluorescence emission spectra were per-
IR spectrum. All spectroscopic results were a puzzle to
us until we obtain a single crystal. The forming structure
is a dinuclear triple‐stranded iron (III)helicate. When we
searched, we saw this iron (III)compound in a few papers
that they all were composed of hydrazine and
salicylaldehyde and either all contained solvate mole-
cules; Et2O,[59] pyridine,[59] benzene,[59] THF,[60]
water,[61] CH3CN,[62] CH2Cl2.[63] In this study, it was first
formed from thiosemicarbazone and ethylenediamine.
Thiosemicarbazones are stable under the standard
conditions, have tautomeric and isomeric structures[64]
and show intermolecular/intramolecular interactions via
nitrogen and hydroxyl oxygen atoms in its structure.
In this study, thiosemicarbazone may have been
decomposed to salicylaldehyde, hydrazine and
carbothioamide fragments by ethylenediamine, and pre-
sumably the fragments went to rearrangements preferring
the most suitable position on account of angular and con-
formational orientation in the presence of iron (III). After
leaving carbothioamide fragmentation, the remaining
fragment was substituted salicylaldehyde fragment by
forming hydrazone compound. The N1, N2‐bis‐(2‐
hydroxy‐benzaldehyde)‐hydrazone structure may show
formed using 10 mmol L−1 Tris–HCl (pH: 7.0).
2.6.5 | Competitive displacement assay
This assay was done by adding EB to the ct‐DNA solu-
tion. The concentration of EB and ct‐DNA was 42 μM
and 17 μM respectively and this solution was titrated with
varying concentration of helicate from 0–11 μM. The EB‐
ct‐DNA complex was excited at 476 nm and emission
spectra were recorded between 500 nm and 800 nm.
3 | RESULTS AND DISCUSSION
At first, we planned to obtain the mixed ligand iron (III)
complex bearing thiosemicarbazone and ethylenediamine
for biological studies. Everything was normal up to results
of elemental microanalysis analyses. The product did not
have a sulphur atom and was containing more nitrogen
atoms than the expected one. In addition, there were not
any vibrational bands corresponding to NH2 or NH in
the regions 3500–3100 cm−1 and 1640–1610 cm−1 in the
TABLE 2 Selected geometric parameters for Helicate
Parameters
X‐Ray
DFT
Parameters
X‐Ray
DFT
Bond lengths (Å)
Fe1─O1
1.891(3)
1.900(4)
1.898(3)
2.133(4)
2.167(4)
2.218(4)
1.279(6)
1.921
N1─N2a
N2─C14
N3─C21
N3─N3a
O1─C1
1.399(5)
1.396
Fe1─O2
1.918
1.942
1.936
1.991
1.969
1.307
1.281(6)
1.273(6)
1.430(7)
1.313(5)
1.310(6)
1.303(6)
1.301
1.302
1.404
1.278
1.284
1.284
Fe1─O3
Fe1─N1
Fe1─N2
Fe1─N3
O2─C8
N1─C7
O3─C15
Bond angles (°)
O1─Fe1─O3
O1─Fe1─O2
O3─Fe1─O2
O1─Fe1─N1
O3─Fe1─N1
O2─Fe1─N1
O1─Fe1─N2
O3─Fe1─N2
O2─Fe1─N2
N1─Fe1─N2
O1─Fe1─N3
94.82(14)
97.50(15)
96.58(15)
84.45(14)
166.29(15)
97.08(15)
170.89(14)
93.88(14)
84.16(14)
86.46(14)
92.23(15)
88.67
86.59
86.27
91.87
178.22
92.07
175.84
89.05
89.79
90.31
91.03
O3─Fe1─N3
O2─Fe1─N3
N1─Fe1─N3
N2─Fe1─N3
C7─N1─N2a
C14─N2─N1a
C21─N3─N3a
N1─C7─C6
83.76(14)
170.20(14)
82.59(14)
86.04(14)
116.2(4)
114.7(4)
117.2(3)
124.5(4)
126.8(5)
124.9(5)
89.14
174.87
92.55
92.42
118.21
118.01
117.76
124.99
125.23
125.53
N2─C14─C13
N3─C21─C20
Symmetry code:
a− x + 3/2, y, −z + 1.

AVCU ALTIPARMAK ET AL.
7 of 14
via one−/two‐dimensional coordination and even more
this ligand could also allow the formation of more complex
three‐dimensional network such as helicates.[10–12,25] In
this study, the formation chose to emerge a helicate, dinu-
clear triple‐stranded iron (III) compound.
The μeff value of the iron (III) compound is the 6.02 B.
M. indicating that it is high‐spin complex. The complex is
very well soluble in polar solvents.
3.1 | Structural analysis
3.1.1 | X‐ray crystallography
The solid‐state structure of the complex has been
unequivocally determined by single‐crystal X‐ray diffrac-
tion. An ORTEP‐3 diagram of the complex with the
atom‐labelling scheme is shown in Figure 1, while rele-
vant bond distances and angles are collected in Table 2
together with their theoretical equivalents. Instead of
the known trigonal structure of the complex,[65] we
obtained a monoclinic polymorph, in space group I2/a,
with four molecules in the unit cell. To the best of our
knowledge, six pseudo‐polymorphs have also been
reported in the literature.[55,59,62,66,67]
There is one‐half of a dinuclear molecule in the asym-
metric unit of the complex, and the equivalent fragments
are inter‐related by the C2 symmetry with a 2‐fold rota-
tion axis passing through the midpoints of Fe1···Fe1i
FIGURE 2 (a) A molecular structure overlap of the monoclinic
(black) and trigonal (red) polymorphs. (b) Superimposition of the
experimental (black) and calculated (red) structures. H atoms have
been omitted for clarity
i
and N3─N3i (Symmetry code: − x + 3/2, y, −z + 1). In
different arrangements around of metal atoms depending
on its flexibility, size of the metal atom and appropriate
stoichiometric ratios. Hydrazone structure could be coor-
dinate face to face with two moles to dinuclear metal
atoms like a linear tube or could be coordinate metal by
turning on the opposite sides around the hydrazine bond
the complex, each of the three ligands coordinates the
two metal ions via two phenolates and two imines acting
as a bis (bidentate) ligand. The metal ions are in facial
O3N3 coordination environments and are connected by
three diaza (═N─N═) bridges to form a binuclear triple
helical structure. The three Fe─N─N─Fe torsion angles
FIGURE 3 Part of the crystal structure
of the complex, showing a π‐stacked pair
of hydrogen‐bonded chains. For the sake
of clarity, only H atoms involved in
hydrogen bonding have been included

8 of 14
AVCU ALTIPARMAK ET AL.
are 44.3(5)° and two symmetry‐equivalent at 65.0(3)°. The
corresponding theoretical values of these angles are 50.56
and 53.44°, respectively. Each iron has a distorted octahe-
dral coordination geometry with a Fe···Fe separation of
3.9498(14) Å, which has been calculated at 3.442 Å. The
average chelate bite angle (84.12°) is smaller than 90°,
while the average trans O─Fe─N angle (169.13°) deviates
substantially from the ideal value of 180°. In addition, the
average N─Fe─N angle (85.03°) is much smaller than the
average O─Fe─O angle (96.3°). Bond distances and
angles are in the normal ranges, and the Fe─O (pheno-
late) and Fe─N (imine) bond lengths are consistent with
the +3 oxidation state of the metal ion.[55,59–62] In the
complex, the ligands are twisted along the N─N single
bonds to accommodate the two metal ions; the dihedral
angle is 5.51(3)° between phenyl rings III and IIIi, and
53.90(2)° between phenyl rings I and IIi, where phenyl
ring I, II and III are defined by the carbon atoms C1 to
C6, C8 to C13 and C15 to C20, respectively. These angles
have been computed as 33.81 and 45.61°, respectively.
As shown by the molecular overlap of the two
polymorphs, there is a conformational difference in their
geometry with an r.m.s. deviation of 0.557 Å (Figure 2a).
When the experimental and optimized structures are
compared, the obtained r.m.s. deviation is 0.672 Å
indicating
a little more conformational disperancy
(Figure 2b).
In the molecular structure of the complex, there are no
intramolecular interactions. In the crystal structure, only
one H‐bonding interaction is observed with the H···A,
D···A and D─H···A geometric parameters being 2.55 Å,
3.399(6) Å and 153°, respectively. In this interaction, atom
C7 in the molecule at (x, y, z) acts as hydrogen‐bond donor
to atom O3 in the molecule at (x − 1/2, −y, z), so generat-
ing an R22ð12Þ ring.[66,67] Propagation of this interaction by
translation and inversion then leads to the formation of a
chain of centrosymmetric R22ð12Þ rings running parallel to
the [100] direction (Figure 3). Finally, two neighboring
chains are linked to each other by means of π─π stacking
interactions between the C1‐C6 benzene rings with a
centroid‐centroid distance of 3.5809(3) Å.
3.1.2 | FT‐IR spectroscopy
The formation of S‐methylthiosemicarbazone was pur-
sued by the emerging peak at 1601 cm−1 attributable
to the azomethine ν (CH=N) on the IR spectrum, which
FIGURE 4 The graphs showing the cell viability obtained by MTT assay in HL‐60, K562, THP‐1 and PBMC treated with different
concentrations of iron (III) helicate.***p < 0.001, **p < 0.05, significant differences between control and each treatment group, ns: not
significant. The results represent the means of at least 3 independent experiments

AVCU ALTIPARMAK ET AL.
9 of 14
has been calculated at 1616 cm−1 [68,69]
.
Upon helicate
thiosemicarbazone, other bands at 3050, 3018 cm−1
C‐H stretching in‐plane, in the range of 2150–
1680 cm−1 a set of small adsorption peaks (overtones)
corresponding to C‐H out‐plane bendings, at 1157,
1148, 1114, 1105 cm−1 assigned to C‐H in‐plane bend-
ings, at 747 and 728 cm−1 related to C‐H out‐plane
bending, at 1571, 1559 cm−1 and 1446 cm−1 related to
C=C vibrations belonging to the aromatic ring were
monitored. These vibrations have been theoretically
observed at 3089 and 2984 cm−1 as CH stretching, at
3024 and 2947 cm−1 as CH3 stretching, at 1608 and
1543 cm−1 as C=C stretching, at 1443 and 1323 cm−1
as CH3 bending, at 1344, 1193 and 1138 cm−1 as CH
in‐plane bending, and at 959, 948 and 739 cm−1 as
CH out‐of‐plane bending.
formation, the ν(C=N) stretching bands were recorded
at 1597 and 1573 cm−1 as dual band, that have been
observed at 1572 and 1547 cm−1, respectively, in the
theoretical spectrum. This is the most important proof
whether azomethine group was coordinated to iron
(III). However, the vibration bands at 3458, 3281 and
1633 cm−1 corresponding to stretching υ (NH2) symmet-
ric, asymmetric, and bending δ (NH) vibrations, respec-
tively, were not observed on the complex spectrum due
to the absence of NH2 and NH groups in the helicate
structure. The asymmetric and symmetric υ (NH2)
stretching, and in‐plane and out‐of‐plane bending δ
(NH2) vibrations have appeared at 3541, 3434, 1585
and 656 cm−1 in the theoretical spectrum, while the υ
(OH) stretching, in‐plane and out‐of‐plane bending δ
(OH) bands have been computed at 3234, 1395 and
On the complex spectrum, the bands assigned to CH in‐
plane bending were monitored at 1144 and 1120 cm−1
,
749 cm−1
,
respectively. In the IR spectrum of
while the CH out‐of‐plane bending band were recorded
FIGURE 5 Representative microscopic images (20X) of all type cells were treated with the helicate by the concentration of 4.24 μM for
72 hr. Left‐hand images are untreated HL‐60 (a), K562 (b), THP‐1 (c) and PBMC (d) as a control group and cells treated with compound
at a concentration of 4.24 μM respectively on the right

10 of 14
AVCU ALTIPARMAK ET AL.
at 753 and 736 cm−1. These signals have been calculated at
1137, 1133, 747 and 741 cm−1, respectively. The C=C
vibrations related to aromatic ring shifted to longer wave-
length, 1536, 1532, 1521, 1519, 1504, 1467 and 1433 cm−1
because of increasing conjugation, which are in good
agreement with the corresponding theoretical results com-
The results of the study demonstrated that the prolifer-
ation of all cell types decreased between 2.72–3.88 μM
concentration as significantly and effectively (Figure 4).
The cytotoxic effect of the helicate on leukemia cells
was very promising. It is important to have good cytotox-
icity and selectivity for compounds of the anti‐cancer
agent potential. In our study, we demonstrated that the
helicate does not damage to healthy PBMC. On the con-
trary to PBMC, it has a cytotoxic effect against leukemia
cells statistically significant. We preferred PBMC as the
control cells because they have a common hematopoietic
origin with leukemia cells.
puted at 1592, 1588, 1502 and 1496 cm−1
.
3.1.3 | UV–vis spectroscopy
The UV–Vis spectrum of starting material in CHCl3
shows four main absorption peaks at 239.5, 293, 304.5,
333.5 and a shoulder at 346.5 nm which could be attribut-
able to the intramolecular charge transfer (ICT) transi-
tions π → π* (B band), n → σ*, and n → π* transition
(R band) corresponding to aromatic ring and phenol,
the latter to azomethine and thioamide groups. In addi-
tion to these peaks, the transitions appearing in the
region of 200–222 nm is related to E2 band can be
assigned to π → π* transitions of benzene group.
The UV spectrum of complex exhibited the bands at
240, 280.5, 377, 444.5 and 514.5 nm attributed to
π → π* and n → π*, Soret band (B band), charge transfer
and d‐d transitions. The band at 346 nm attributable to
thioamide of starting material did not appear on the com-
plex spectrum due to fragmentation. The excited struc-
ture became more stable by increasing conjugation
because there was delocalization of the pi bonding
orbitals over the whole molecule after complexation.
Therefore, the more the delocalization, the longer the
wavelength absorbed. That is, it was observed shifting to
longer wavelengths to red with less energy.
FIGURE 6 UV–Vis absorption spectra of helicate in the presence
of increasing amounts of ct‐DNA (pH:7.0, 10 mM Tris–HCl), C
Helicate = [51.3 μg/mL], CDNA = 28 μM (the amount of addition
0.028, 0.056, 0.11, 0.22, 0.55, 1.1, 2.1, 3, 4.7 μM) for curves 1–9,
respectively
3.2 | Cytotoxic results
In this study, we used HL‐60, K562, and THP‐1 cells as
leukemia cell lines and PBMC as control cells. After treat-
ment with helicate for 72 hrs, we determined the percent-
age of cell viability. We investigated the concentrations of
1.21, 4.24, 6.06, 8.48 and 12.11 μg/ml of the helicate in
cells (Figure 4).
TABLE 3 The IC50 (half‐maximal inhibitory concentration)
values of leukaemia cells treated with the helicate and Vincristine
are shown for 72 hr‐treatment
Cell line
IC50 (μM) Helicate
IC50 (μM) Vincristine*
HL‐60
K562
2,72 0,85
3,46 0,40
3,88 0,63
4,72 μM 0,61
7,03 μM 0,13
5,58 μM 0,27
THP‐1
*Vincristine is used as positive control.
FIGURE 7 The plot of [DNA]/(εa‐εf) versus [DNA]

AVCU ALTIPARMAK ET AL.
11 of 14
Considering the results of both cell culture appear-
ances and MTT tests, it was seen to be effective in all leu-
kemia cells. Especially, the cytotoxic effect was more
prominent in HL‐60 cells that acute myeloid leukemia
because it has the lowest IC50 value (Figure 5). As a
result, IC50 values of all cells were obtained by MTT assay
for 72 hours and the calculated IC50 values were given in
Table 3.
When we searched dinuclear metal complexes includ-
ing Ar‐C=N‐N=C‐Ar (Ar = 2‐hydroxyaryl) framework in
the Cambridge Structural Database (CSD, version
5.40)[70] by using ConQuest software (version 2.0.1),[71]
there have been eighty‐four compounds so far. Almost
all are on synthesis, magnetic, catalytic, thermal and
electrochemical properties of the complexes. We found
only two studies about biological activities of the com-
plexes, one on cytotoxicity[72] and another on DNA
binding.[73]
strength of the interaction between the small molecules
and DNA as seen in Figure 6.
The intrinsic binding constant Kb for helicate was calcu-
lated as 8×106 M−1 (Figure 7). This Kb value is the same
order that reported for ethidium bromide whose binding
constant has been reported to be in the order of 106–
107 M−1 and indicates the strong binding affinity of
helicate towards ct‐DNA. Intercalation mode between
helicate and ct‐DNA are considered to be most indicate
intercalative binding.[30,55,74] Further studies are necessary
to confirm the binding mode of helicate to DNA hence
more experimental data is needed, therefore fluorescence
was a good tool to get information about the binding mode.
3.3.2 | Fluorescence studies
The enhancement of fluorescence emission is expected,
due to observed hypochromism in the absorption spectra
of helicate upon addition of DNA as a result of helicate
binding to DNA.[75,76] A 50% increase of fluorescence
emission was observed after adding DNA (Figure 8a).
As seen from Figure 8a the fluorescence intensity
gradually increases in the presence of DNA, consistent
with complex formation. The apparent binding constant
K (M−1) was calculated from the Scatchard equation,
the slope of a plot of [(F0‐ F/F0) / [Q]] versus (F0‐ F/F0)
and n by the ratio of the y intercept to the slope according
to equation 3 (Figure 8b).
In the article by S. Pasayat et al,[72] dimeric and
tetrameric oxidomolybdenum (VI) complexes of N,N′‐
disalicyloylhydrazine, complex 1 and complex 2, has
32,66 μM and 28,33 μM IC50 values in Hela cells,
respectively. In this study both different cell lines are
used and IC50 values are higher than IC values of our
complex.
3.3 | DNA binding results
3.3.1 | Absorption properties
Fo − F
Fo
Fo − F
¼ nK − K
(3)
Fo
The absorption studies of the helicate compound upon
addition of ct‐DNA solution are useful to determine the
binding mode. The addition of certain amounts of DNA
resulted in decreasing the absorption spectrum and dena-
turation was not observed even at higher DNA concentra-
tions (Figure 6). Hypochromism is evidence of the
½Qꢀ
where F0 is the initial fluorescence intensity of complex,
F is the fluorescence intensity of the complex after addi-
tion of ct‐DNA, n is the number of binding sites per ct‐
DNA, and K is the apparent binding constant.
FIGURE 8 a) Fluorescence emission spectra of helicate by varying amounts of ct‐DNA (pH:7, 10 mM Tris‐ HCl, λex = 320 nm),
CHelicate = 62 μM, (the amount of addition 0.028, 0.056, 0.11, 0.22, 0.55, 1.1, 2.1, 3, 4.7 μM) for curves 1–8, respectively. b) Scatchard plot
of binding analysis

12 of 14
AVCU ALTIPARMAK ET AL.
The binding constant was calculated as 8.9x106 M−1
,
which is slightly less than the binding constants
of the classical intercalators and metallointercalators
(107 M−1 [77]
and stoichiometry (n) 0.35. The binding
)
constant obtained from this experiment is in quite good
agreement with that from the absorption titration
experiments.
Obtained results from UV absorption and fluorescence
emission display that the helicate possibly bind to ct‐
DNA by intercalation binding mode.
3.3.3 | Competitive displacement assay
EB can produce an intense fluorescence emission in the
presence of ct‐DNA as a result of strong intercalation
and the fluorescence emission intensity will be quenched
after the addition of a second molecule if molecule
replacing it. In order to determine the ability of helicate
to displace EB from intercalated complexes between EB
and ct‐DNA, an EB displacement assay was conducted
as shown in Figure 9. Indeed, addition of helicate indi-
cated a progressive decrease in the DNA‐induced EB
emission, due to the displacement of EB by helicate.
The quenching of EB bound to ct‐DNA by helicate is
in good agreement with the linear Stern‐Volmer
equation (4), which provides further evidence that the
compound helicate bind to DNA (Figure 10).
FIGURE 10 Stern‐Volmer Plot of the quenching of fluorescence
of EB‐bound to DNA in the presence of helicate
When have been searched dinuclear metal complexes
including Ar‐C=N‐N=C‐Ar (Ar = 2‐hydroxyaryl) group
in the CSD.[70]by using ConQuest software (version
2.0.1),[71] it was seen that the DNA binding activity of
only one compound (Zn3L3 type complex) in 84 com-
pounds was studied by Mishra MK et al.[73] The binding
constant Kb was reported as 7.6x 105 M−1 for Zn3L3 type
complex nearly 10 times lower than our helicate‐DNA
complex (Kb = 8×106 M−1) and Ksv value of EB displace-
ment experiment by helicate was found much higher
compare to Zn3L3(Ksv (helicate) =1.45x 104 M−1
> > Ksv (Zn3L3) =0.2333 M−1).[73]
F0= F ¼ 1 þ KSV½Qꢀ
(4)
The Ksv value for helicate was calculated as 1.45×104 L
mol−1 which indicates strong binding.
4 | CONCLUSIONS
The reaction of a thiosemicarbazone compound and
ethylenediamine in the presence of iron (III)chloride
yielded a dinuclear triple‐stranded iron (III)helicate struc-
ture, Dinuclear iron (III) complex of tris(N1, N2‐bis‐(2‐
hydroxy‐benzaldehyde)‐hydrazone), unexpectedly. This is
the first helicate formation via a thiosemicarbazone as
far as we know. In solid state structure, helicate units
are connected to each other by π─π stacking interactions
and C─H···O intermolecular interactions and generate a
porous supramolecular structure. Cytotoxic activity
results against K562, HL‐60 and THP‐1 leukaemia cells
show that helicate has spectacular cytotoxicity in low
concentrations compared to control PBMC. Even IC50
value of vincristine used as a positive control is nearly 2
times bigger than that of the helicate.
FIGURE 9 Fluorescence titration of the EB‐ct‐DNA complex
with increasing amount helicate. (λex = 476 nm,). CEB = 42 μM,
CDNA =17 μM, CHelicate = 0.26, 0.51, 1.3, 2.5, 4.8, 6.9, 11 μM. The
arrow indicates the fluorescence decreases upon increasing helicate
concentrations
The helicate exhibits a high binding affinity for ct‐
DNA. Absorption and fluorescence emission studies and
competitive displacement assay results support that

AVCU ALTIPARMAK ET AL.
13 of 14
Siegel, J. Harrowfield, B. Chevrier, D. Moras, Proc. Natl. Acad.
Sci. U. S. a. 1987, 84, 2565.
helicate binds to ct‐DNA by intercalative mode. These
results indicate that the iron (III) helicate become a new
candidate of anticancer drugs, because such strong
binding to DNAs should prevent the proliferation of the
cancer cells and they introduce to death.
[12] C. Piguet, M. Borkovec, J. Hamacek, K. Zeckert, Coord. Chem.
Rev. 2005, 249, 705.
[13] T. R. Cook, V. Vajpayee, M. H. Lee, P. J. Stang, K. Chi, Acc.
Chem. Res. 2013, 46, 2464.
[14] T. Miao, Q. Deng, H. Gao, X. Fu, S. Li, J. Chem. Inf. Model.
2018, 58, 859.
ACKNOWLEDGEMENTS
[15] A. Oleksy, A. G. Blanco, R. Boer, I. Usón, J. Aymamí, A.
Rodger, M. J. Hannon, M. Coll, Angew. Chem. Int. Ed. 2006,
45, 1227.
This work is a part of a master's thesis of Elif Avcu
Altıparmak and was supported by the Scientific Research
Projects Coordination Unit of İstanbul University (Project
Number: FYL‐2017‐23739) and by Ondokuz Mayıs Univer-
sity (Project No: PYO.FEN.1906.19.001). We also thank
Amasya University, Turkey, for accessing to GaussView
5.0 and Gaussian 09 W program packages.
[16] H. Furukawa, K. E. Cordova, M. O'Keeffe, O. M. Yaghi, Science
2013, 341, 1230444.
[17] Y. Haketa, H. Maeda, Chem. – Eur. J. 2011, 17, 1485.
[18] C. Pariya, C. R. Sparrow, C. K. Back, G. Sandi, F. R. Fronczek,
A. W. Maverick, Angew. Chem. Int. Ed. 2007, 46, 6305.
[19] S. Ghosh, D. R. Turner, S. R. Batten, P. S. Mukherjee, Dalton
Trans. 2007, 1869.
ORCID
[20] Y. Okuno, K. Uoto, O. Yonemitsu, T. Tomohiro, J. Chem. Soc.,
Chem. Commun. 1987, 1018.
Elif Avcu Altiparmak
https://orcid.org/0000-0002-5491-
8445
[21] R. D. Schnebeck, E. Freisinger, B. Lippert, Chem. Commun.
1999, 675.
Guneş Ozen Eroglu https://orcid.org/0000-0003-3681-9336
Elif Ozcelik https://orcid.org/0000-0002-8086-4129
Namık Özdemir https://orcid.org/0000-0003-3371-9874
[22] F. Gao, H. Chao, F. Zhou, Y.‐X. Yuan, B. Peng, L.‐N. Ji, J. Inorg.
Biochem. 2006, 100, 1487.
Serap Erdem Kuruca
9994
Nergis Arsu https://orcid.org/0000-0002-1362-2517
Bahri Ülküseven https://orcid.org/0000-0001-6342-1505
Tulay Bal‐Demirci https://orcid.org/0000-0003-4663-2209
https://orcid.org/0000-0001-7878-
[23] (a)J. Malina, M. J. Hannon, V. Brabec, Chem. – Eur. J. 2015, 21,
11189. (b)J. Malina, P. Scott, V. Brabec, Dalton Trans. 2015, 44,
14656. (c)S. E. Howson, A. Bolhuis, V. Brabec, G. J. Clarkson, J.
Malina, A. Rodger, P. Scott, Nat. Chem. 2012, 4, 31. (d)R. A.
Kaner, S. J. Allison, A. D. Faulkner, R. M. Phillips, D. I. Roper,
S. L. Shepherd, D. H. Simpson, N. R. Waterfield, P. Scott, Chem.
Sci. 2016, 7, 951. (e)S. M. McNeill, D. Preston, J. E. M. Lewis, A.
Robert, K. Knerr‐Rupp, D. O. Graham, J. R. Wright, G. I. Giles,
J. D. Crowley, Dalton Trans. 2015, 44, 11129.
REFERENCES
[1] J. Bernstein, H. L. Yale, K. Losee, M. Holsing, J. Martins, W. A.
[24] (a)A. D. Richards, A. Rodger, M. J. Hannon, A. Bolhuis, Int. J.
Antimicrob. Agents 2009, 33, 469. (b)S. V. Kumar, W. K. C. Lo,
H. J. L. Brooks, J. D. Crowley, Inorg. Chim. Acta 2015, 425, 1.
Lott, J. Am. Chem. Soc. 1951, 73, 906.
[2] R. Yanardag, T. Bal‐Demirci, B. Ülküseven, S. Bolkent, S.
Tunali, S. Bolkent, Eur. J. Med. Chem. 2009, 44, 818.
[25] A. C. G. Hotze, N. J. Hodges, R. E. Hayden, C. Sanchez‐Cano,
C. Paines, N. Male, M. K. Tse, C. M. Bunce, J. K. Chipman,
M. J. Hannon, Chem. Biol. 2008, 15, 1258.
[3] J. Patole, S. Padhye, M. S. Moodbidri, N. Shirsat, Eur. J. Med.
Chem. 2005, 40, 1052.
[4] T. Bal‐Demirci, G. Congur, A. Erdem, S. Erdem‐Kuruca, N.
Özdemir, K. Akgün‐Dar, B. Varol, B. Ülküseven, New J. Chem.
2015, 39, 5643.
[26] A. C. G. Hotze, B. M. Kariuki, M. J. Hannon, Angew. Chem. Int.
Ed. 2006, 45, 4839.
[27] V. Brabec, O. Hrabina, J. Kasparkova, Coord. Chem. Rev. 2017,
351, 2.
[5] A. Kumar Das, S. Goswami, Sens. Actuators B 2017, 245, 1062.
[6] T. Bal‐Demirci, M. Akkurt, Ş. P. Yalçın, O. Büyükgüngör, Tran-
sition Met. Chem. 2010, 35, 95.
[28] K. Nakamato, M. Tsuboi, G. D. Strahan, Drug‐DNA Interac-
tions: Structures and Spectra, John Wiley
Hobojen, NJ 2008.
& Sons Inc.,
[7] D. X. West, A. E. Liberta, S. B. Padhye, R. C. Chikate, P. B.
Sonawane, A. S. Kumbhar, R. G. Yerande, Coord. Chem. Rev.
1993, 123, 49.
[29] S. U. Rehman, T. Sarwar, M. A. Husain, H. M. Ishqi, Arch.
Biochem. Biophys. 2015, 576, 49.
[8] D. Palanimuthu, R. Poon, S. Sahni, R. Anjum, D. Hibbs, H.‐Y.
Lin, P. V. Bernhardt, D. S. Kalinowski, D. R. Richardson, Eur. J.
Med. Chem. 2017, 139, 612.
[30] M. Sirajuddin, S. Ali, A. Badshah, J. Photochem. Photobiol. B
2013, 124, 1.
[31] M. J. Hannon, V. Moreno, M. J. Prieto, E. Molderheim, E.
Sletten, I. Meistermann, C. J. Isaac, K. J. Sanders, A. Rodger,
Angew. Chem. Int. Ed. 2001, 40, 879.
[9] M. Albrecht, Chem. Soc. Rev. 1998, 27, 281.
[10] J. W. Steed, J. L. Atwood, Supramolecular Chemistry, John
Wiley and Sons, Chichester 2000.
[32] A. D. Faulkner, R. A. Kaner, Q. M. A. Abdallah, G. Clarkson,
D. J. Fox, P. Gurnani, S. E. Howson, R. M. Phillips, D. I. Roper,
D. H. Simpson, P. Scott, Nat. Chem. 2014, 6, 797.
[11] (a)J.‐M. Lehn, Supramolecular Chemistry: Concepts and Per-
spectives, VCH, Weinheim 1995. (b)J.‐M. Lehn, A. Rigault, J.

14 of 14
AVCU ALTIPARMAK ET AL.
[33] V. Brabec, S. E. Howson, R. A. Kaner, R. M. Lord, J. Malina, R.
M. Phillips, Q. M. A. Abdallah, P. C. McGowan, A. Rodger, P.
Scott, Chem. Sci. 2013, 4, 4407.
[59] M. Hong, F. Chen‐jie, D. Chun‐ying, L. Yu‐ting, M. Qing‐jin,
Dalton Trans. 2003, 7, 1229.
[60] J. Wang, B. Liu, B. Yang, Acta Crystallogr., Sect. E: Struct. Rep.
Online 2008, 64, m1210.
[34] L. Cardo, V. Sadovnikova, S. Phongtongpasuk, N. J. Hodges, M.
J. Hannon, Chem. Commun. 2011, 47, 6575.
[61] F. ‐F. Jian, C. ‐Y. Zhu, H. ‐L. Xiao, L. ‐Z. Xu, Z. Anorg. Allg.
Chem. 2005, 631, 769.
[35] J. Li, T. Murakami, M. Higuchi, J. Inorg. Organomet. Polym.
2013, 23, 119.
[62] J. Saroja, V. Manivannan, P. Chakraborty, S. Pa1, Inorg. Chem.
1995, 34, 3099.
[36] N. Ataci, E. Ozcelik, N. Arsu, Spectrochim. Acta A 2018, 204, 281.
[37] N. Ataci, N. Arsu, Spectrochim. Acta A 2016, 169, 128.
[38] T. Bal‐Demirci, Polyhedron 2008, 27, 440.
[63] S. G. Sreerama, S. Pal, Inorg. Chem. 2005, 44, 6299.
[64] C. Yamazaki, Can. J. Chem. 1975, 53, 610.
[65] L. Yan, S. Ding, Y. Ji, Z. Liu, C. Liu, J. Coord. Chem. 2011, 64,
[39] Stoe & Cie, X‐AREA Version 1.18 and X‐RED32 Version 1.04,
Stoe & Cie, Darmstadt, Germany 2002.
3531.
[66] J. ‐W. Ran, S. ‐W. Liu, P. Wu, J. Pei, Chin. Chem. Lett. 2013, 24,
[40] G. M. Sheldrick, Acta Crystallogr. A 2015, 71, 3.
[41] G. M. Sheldrick, Acta Crystallogr. C 2015, 71, 3.
[42] L. J. Farrugia, J. Appl. Crystallogr. 2012, 45, 849.
[43] T. Mosmann, J. Immunol. Methods 1983, 65, 55.
373.
[67] J. Bernstein, R. E. Davis, L. Shimoni, N. L. Chang, Angew.
Chem. Int. Ed. 1995, 34, 1555.
[68] Ş. Güveli, T. Bal‐Demirci, B. Ülküseven, N. Özdemir,
Polyhedron 2016, 110, 188.
[44] R. Dennington, T. A. Keith, J. M. Millam, GaussView, Version
5.0, Semichem, Inc., Shawnee Mission, KS 2009.
[69] M. Şahin, A. Koca, N. Özdemir, M. Dinçer, O. Büyükgüngör, T.
Bal‐Demirci, Dalton Trans. 2010, 39, 10228.
[45] M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A.
Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci,
G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P.
Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L.
Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J.
Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H.
Nakai, T. Vreven, J. A. Montgomery Jr., J. E. Peralta, F. Ogliaro,
M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N.
Staroverov, R. Kobayashi, J. Normand, K. Raghavachari, A.
Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega,
J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C.
Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev,
A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L.
Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salva-
dor, J. J. Dannenberg, S. Dapprich, A. D. Daniels, Ö. Farkas, J.
B. Foresman, J. V. Ortiz, J. Cioslowski, D. J. Fox, Gaussian
09W, Revision C.01, Gaussian, Inc., Wallingford, CT 2009.
[70] C. R. Groom, I. J. Bruno, M. P. Lightfoot, S. C. Ward, Acta
Crystallogr. B 2016, 72, 171.
[71] I. J. Bruno, J. C. Cole, P. R. Edgington, M. Kessler, C. F.
Macrae, P. McCabe, J. Pearson, R. Taylor, Acta Crystallogr. B
2002, 58, 389.
[72] S. Pasayat, S. P. Dash, S. Majumder, R. Dinda, E. Sinn, H.
Stoeckli‐Evans, S. Mukhopadhyay, S. K. Bhutia, P. Mitra, Poly-
hedron 2014, 80, 198.
[73] R. K. Mishra, K. K. Upadhyay, S. Shukla, R. Mishra, Chem.
Commun. 2012, 48, 4238.
[74] M. J. Waring, J. Mol. Biol. 1965, 13, 269.
[75] H. Chen, S. Li, Y. Yao, L. Zhou, J. Zhao, Y. Gu, K. Wang, X. Li,
Bioorg. Med. Chem. Lett. 2013, 23, 4785.
[76] A. K. Williams, S. C. Dasilva, A. Bhatta, B. Rawal, M. Liu, Anal.
Biochem. 2012, 422, 66.
[46] A. D. Becke, J. Chem. Phys. 1993, 98, 5648.
[77] M. Cory, D. D. McKee, J. Kagan, D. W. Henry, J. A. Miller,
[47] C. Lee, W. Yang, R. G. Parr, Phys. Rev. B 1988, 37, 785.
J. Am. Chem. Soc. 1985, 107, 2528.
[48] R. Krishnan, J. S. Binkley, R. Seeger, J. A. Pople, J. Chem. Phys.
1980, 72, 650.
SUPPORTING INFORMATION
[49] M. J. Frisch, J. A. Pople, J. S. Binkley, J. Chem. Phys. 1984, 80,
Additional supporting information may be found online
in the Supporting Information section at the end of the
article.
3265.
[50] P. J. Hay, W. R. Wadt, J. Chem. Phys. 1985, 82, 270.
[51] P. J. Hay, W. R. Wadt, J. Chem. Phys. 1985, 82, 284.
[52] P. J. Hay, W. R. Wadt, J. Chem. Phys. 1985, 82, 299.
[53] M. P. Andersson, P. Uvdal, J. Phys. Chem. A 2005, 109, 2937.
[54] R. Shen, W. Wang, G. Yang, J. Fluoresc. 2014, 24, 959.
How to cite this article: Avcu Altiparmak E,
Ozen Eroglu G, Ozcelik E, et al. The formation of a
metallosupramolecular porous helicate through
salicylaldehydethiosemicarbazone: Synthesis,
Characterization, Cytotoxic activity, DNA binding
and DFT calculations. Appl Organometal Chem.
2019;e5023. https://doi.org/10.1002/aoc.5023
[55] S. Kashanian, M. M. Khodaei, P. Pakravan, DNA Cell Biol.
2010, 29, 639.
[56] E. Tuite, U. Sehilstedt, P. Hagmar, B. Norden, M. Takahashi,
Eur. J. Biochem. 1997, 243, 482.
[57] S. Kashanian, S. Heidary, H. Zeidali, K. Omidfar, N. Shahabadi,
Mol. Biol. Rep. 2012, 39, 10045.
[58] N. Shahabadi, M. Maghsudi, Dyes Pigm. 2013, 96, 377.